1. Field of the Invention
Relates to air-to-air missiles and more particularly to air-to-air missiles having homing devices and guidance systems to direct the missile to the target.
2. Discussion of the Problem to be Solves and the Prior Art
To penetrate enemy territory, a bomber must fly at low altitudes and utilize electronic counter measures (ECM) to reduce the effectiveness of radar detection and tracking. There is no active defense other than a radar-directed tail gun system. The effectiveness of the gun has been demonstrated in Southeast Asia, where two interceptors were destroyed without corresponding loss of bombers. Unfortunately, at low altitudes, the gun has questionable fire control radar performance and the bomber is reduced to a passive, undefended target. Once an interceptor succeeds in gaining visual or infrared contact, he may proceed virtually without interference to an optimum weapon launching position.
The most critical attack area for a bomber is the rear quadrant, particularly with infrared guided missiles. The higher closing velocities and line-of-sight rates from the front and side quadrants will significantly reduce missile kill probabilities. Typical launch envelopes for a Mach 0.9 interceptor against a bomber are 2.2 nautical miles (n.m.) over.+-.45.degree. tail aspect angle, or for a more advanced infrared guided weapon 3.0 n.m. over a.+-.60.degree. aximuthal sector.
To offset bomber vulnerability, a number of defense missiles have been proposed. The major problem has been getting these missiles turned into the rear quadrant. They must be either launched forward and turned 180.degree. after launch, or launched to the rear with an awkward stability transition through zero speed. In order to execute these maneuvers and retain rear quadrant range, some of the resultant missiles have been as large as offensive missiles which impacts the bomber's offensive payload. These missiles inherently have greater performance in the front and side quadrants and have been matched with fire control radars to exploit the full missile capability. As a result, the threat detection, fire control, and missile guidance systems have become inordinately complex, sophisticated and costly.
The proposed Self Defense Missile (SDM) concept is based on the premise of protecting the critical rear quadrant. The concept employs unpowered missiles which are released from the bomber and fly a nominal mid-course trajectory based on threat position and velocity at time of launch.
The threat detection and tracking is accomplished using a radar which has been designed for low altitude operation and is modified for the SDM application to provide increased angle accuracy.
The SDM mid-course is intermittantly revised by the fire control system to counter changes in the threat trajectory. An infrared (IR) seeker or the like at the aft end of the SDM is utilized for the terminal guidance. The IR seeker locks-on after launch. The bomber fire control system transmits IR seeker aiming information to reduce the IR search volume and to enhance target acquisition.
The SDM concept provides a minimum impact defense system since a new threat detection system is not required. The terminal guidance seeker technology and hardware are currently available which reduces the SDM development. The fire control system is greatly simplified, since angle accuracy and data rate requirements are minimal and coverage is limited to the rear. All of these factors combine to significantly reduce the cost of the SDM as compared to other missile defense systems.
In addition, the unpowered Self Defense Missile concept has some unique advantages over other approaches to the self defense problem. The control system is simplified since the missile does not have to execute a 180 degree turn. The lack of a propulsion system significantly reduces the missile size, eliminates at least one-fifth of the expense and complexity, and also makes both ends of the missile available for sensors and antennas. Compared to powered missiles, installation of the SDM on a bomber allows more missiles to be carried for the same weight. The missile environment for the sensors and guidance and control components is less demanding in terms of `g` loads, vibration, and heating. Without a rocket propulsion system, the storage, handling, reliability and safety are improved. Due to the small size and lack of propulsion system smoke and heat, the optical, radar and I.R. visibility will be very low, thereby minimizing the chance for enemy detection of this defense concept.